Carbon fiber reinforced thermoplastic plastic composites, in which carbon fibers are dispersed in matrix resin, are utilized in broad areas such as automobiles, planes, electrical/electronic optical devices, precision devices, amusement/toys, home/office products, construction materials, etc. in terms of being excellent in light weight, dynamic characteristics, dimensional stability, conductivity, etc., and its demand is increasing yearly.
For a method of obtaining formable substrates from this carbon fiber reinforced thermoplastic plastic composite, a method for impregnating carbon fibers in a tub comprising matrix resin, etc. may be given.
To industrially stably form a high quality carbon fiber reinforced thermoplastic plastic composite, in an impregnation process in which matrix fiber is impregnated in carbon fibers, a carbon fiber bundle comprising thousands of filaments and carrying out matrix fiber impregnation easily and completely is required.
But, because carbon fibers have low elongation, and vulnerable properties, lint may be easily be generated from mechanical friction, and also lacks wettability in respect to matrix resin. Because of this, it is difficult for carbon fibers used as strengthening agents to have excellent properties as described above. To improve this, until now, treatment by sizing agents is carried out in respect to carbon fibers used in strengthening agents of fiber reinforced thermoplastic plastic composites. That is, by carrying out treatment by sizing agents in carbon fibers, along with improving handling of carbon fibers, wettability of matrix resin is also improved.
As an example of this sizing agent, a condensate of epoxy resin, unsaturated dibasic acid, and alkylene oxide adduct of phenol, and a sizing agent alkylene oxide adduct having alkylene oxide adduct of phenol as an essential component was proposed. Also, a sizing agent composed of epoxy resin, alkylene oxide adduct of monocyclic or polycyclic phenol and unsaturated dibasic acid or its ester forming derivative, and a polyester condensate of acid value of 40 or below with alkylene oxide adduct of bisphenol was proposed. Generally, in carbon fiber reinforced thermoplastic plastic composites in which carbon fibers are dispersed in matrix resin, as carbon fibers are dispersed into single fibers, it is advantageous in uniformity of characteristics and surface appearance quality. But in the case of sizing treatment of carbon fibers, it inherits problems of mechanical properties of carbon fiber reinforced thermoplastic plastic composites degrading in accordance with spreading characteristics of carbon fiber bundles in impregnation process.
Meanwhile, for manufacturing fiber reinforced thermoplastic plastics using continuous carbon fibers, normally filaments having 3000 fiber bundles are used. In the case of continuous carbon fiber reinforced thermoplastic plastic composites having 3000 fiber bundles, it inherits problems of having high manufacturing costs due to high raw material costs and low productivity. For related prior publications, there is Japan laid-open patent JP 2009-263406 (made public Nov. 12, 2009).